The Russian invasion of the Crimean peninsula and the haunting fear that Moscow will use its energy exports to bludgeon Ukraine and the European Union into compliance have unleashed a cavalcade of calls for the United States to use its own energy bounty to rescue Europe. Gazprom’s threat on Friday to shut off gas supplies to Ukraine, which owes the company almost $2 billion and is late with the payments, has added fuel to the fire.

There’s just one problem: While there is one abundant U.S. energy source that could help Europe in the short term, it isn’t natural gas. The United States won’t be able to export significant amounts of liquefied natural gas (LNG) for years, much of that gas has already been snapped up by customers with long-term contracts, and Europe must compete with Asia, which is willing to pay far more money for the little that is left.

That may come as news to Congress, where top lawmakers are arguing that stepping up gas exports to Ukraine would be an easy way to boost the country’s new, fragile, and pro-Western government. House Speaker John Boehner (R-Ohio) took to the opinion pages of the Wall Street Journal to call on the United States to "liberate" its "natural energy" as a weapon against Russian strongman Vladimir Putin by accelerating a sclerotic permitting process for natural gas export terminals. Numerous members of Congress are rushing to introduce, or reintroduce, legislation meant to fast-track exports of U.S. gas. Rep. Michael Turner (R-Ohio), for instance, introduced a bill on Thursday, March 6, that would expand U.S. gas exports to all World Trade Organization countries.

Late Thursday, the ambassadors to the United States from Hungary, Poland, the Czech Republic, and Slovakia sent letters to Boehner and Senate Majority Leader Harry Reid (D-Nev.) urging Congress to unshackle U.S. gas exports and help allies in Europe.

Jason Bordoff, a former energy advisor to President Barack Obama, argued on ForeignPolicy.com that the United States can turn gas to its advantage against Russia. The Heritage Foundation wants U.S. gas to bolster allies in the Baltics. TheNew York Times and theWall Street Journal have reported on the frenzy in Washington to turn energy abundance into geopolitical leverage, including the State Department’s push to use natural gas as a diplomatic tool. The basic thrust: Awash in natural gas, the United States needs to release the hounds, as it were, on Russia.

Those calls miss a fundamental point: Simply making it easier for the United States to export gas won’t automatically translate into help for beleaguered friends, especially because customers in Asia are willing and able to pay higher prices for gas than anyone else.

"You can issue all the permits you want. Gas companies still won’t lose money on purpose to help the United States achieve geopolitical gains," Michael Levi, an energy expert at the Council on Foreign Relations, told Foreign Policy. He wrote about the limits of U.S. gas diplomacy earlier this week.

That isn’t to say that energy exports wouldn’t serve U.S. interests over the longer term, as Bordoff noted. The hydraulic fracturing revolution over the last five years has unleashed a gusher of natural gas supplies that have already reshaped the U.S. electricity sector and reinvigorated certain manufacturing sectors and that hold promise as an alternative fuel for transportation.

Shipping some of that gas, and eventually oil unleashed by the same process, overseas would certainly help the U.S. trade balance and add liquidity to global markets. More supplies of oil and gas sloshing around the globe would reduce the likelihood of supply shocks and buffer economies against price spikes. Greater global supplies also make certain foreign-policy objectives, such as slapping sanctions on Iran’s oil exports, easier to do with less pain.

But that doesn’t mean that the United States is in a position to use its gas supplies to ride to Ukraine’s or Europe’s rescue right now, when Moscow is jacking up prices of the gas it ships west and hinting at a supply stoppage to Kiev.

First and foremost, it takes years and billions of dollars to construct the specialized terminals needed to convert natural gas into a liquid and then cram it into specially built tankers. The Energy Department has approved six of the 30-odd applications it has for LNG export terminals to sell gas to countries with which the United States does not have a free trade agreement. But only one project, Cheniere Energy’s export terminal in Sabine Pass, La., has passed all the regulatory hurdles and secured final authorization. It hopes to begin exports late next year; few if any of the remaining terminals waiting in line will be operational before 2018.

"We only have one approved license actually, and the molecules still aren’t going to flow for a while," Energy Secretary Ernest Moniz said at a conference this week in Houston, Bloomberg reported.

On paper, there is enough potential gas included in the pending export applications to meet two-thirds of Europe’s annual gas consumption. Even if only a handful of terminals are finally built, the potential gas volumes available for export could still theoretically meet a significant part of Europe’s needs, which are estimated at about 18 trillion cubic feet of gas per year.

In reality, exporters need to secure long-term supply contracts with dedicated customers before they can secure the billions of dollars they need to build the advanced LNG terminals. Terminals that have already won conditional approval have supply contracts with power companies in Japan, South Korea, and India. Japanese firms, for example, have secured supply deals with four of the six terminals that have won Energy Department approval so far. Only a handful of European firms have signed long-term contracts with U.S. LNG exporters.

And only a small portion of the contracts are for so-called portfolio gas sales, where the buyer can ship gas wherever it’s needed — which is what Europe would need as a safety valve to replace Russian supplies. In other words, even when the U.S. export terminals are up and running at full speed in four years or so, most of their gas will be earmarked for Asia.

Another complication is the price of exported gas. Until recently, natural gas was cheap inside the United States because of a sheer glut of supply, not the fracking revolution. For the last couple of years, natural gas cost between $2 and $4 per million British thermal units (Btu) at Henry Hub, the main U.S. pricing point. But a vicious winter has sent gas use and gas prices soaring; in the first week of March, Henry Hub prices topped $7.

That matters for exports, because gas has to be liquefied and transported thousands of miles, which adds to the market price of the gas. Shipments from the United States to Europe are expected to add about $4 to the price of gas, while the longer route to Asia will likely add about $6 to the price. As natural gas becomes pricier at home, it becomes harder for U.S. gas to undercut gas overseas. Much of Europe pays around $10 to $11 per million Btu for Russian gas, for example — which would already make it tough for U.S. gas to compete.

In Asia, LNG fetches higher prices than in other parts of the world — about $15 per million Btu. That does provide a market for U.S. exports, especially since Japan needs gas to replace its shuttered nuclear fleet, and China hopes to boost the use of gas to clean up its power sector. But it also means that gas exporters will look first to customers in Asia that are willing to pay a premium rather than to the ones in Europe that aren’t.

The United States does have one energy arrow in its quiver that could meet some of Europe’s needs, but it isn’t one the Obama administration is racing to embrace, or one that thrills European greens: cheap, abundant, U.S. coal.

In recent years, the gas boom has knocked King Coal off its perch in the U.S. market; overseas markets became a natural replacement. The United States set a record for coal exports in 2012, and despite an apparent drop-off in 2013, it still had one of its biggest export years ever. Despite all the talk of China’s insatiable thirst for coal, Europe was — and remains — the biggest export market for U.S. coal.

Unlike with natural gas, coal-export facilities are already up and running. Unlike the convoluted regulations governing natural gas exports, coal can be traded freely. And there’s no need for European countries to build expensive new terminals to handle coal imports.

There is one problem, of course: Coal is a lot dirtier than gas, with about twice the emissions of greenhouse gases when burned for power. For years, Europe has tried to curb its emissions and make its energy sector cleaner, even though expensive local gas and cheap U.S. coal have made that tough the last couple of years.

But as Europe grapples with long-term questions of energy security, climate change goals, and fears about economic competitiveness, coupled with short-term fears about a sudden end to energy supplies from Moscow, coal might just be the one U.S. energy export that makes a difference.